Seat back



FIG. 1 is an upper perspective view of the seat back showing my design.

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is an opposite side view thereof;

FIG. 6 is top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is another upper perspective view of a second embodiment, the difference being a matter of length; and,

FIG. 9 is an upper perspective view thereof, showing attachment to a seat in broken lines.

The broken lines in FIG. 9 are presented for illustrative purposes only and for no part of the claimed design. 

The ornamental design for a seat back, as shown and described. 